Probing parsec scale jets in AGN with geodetic VLBI

TL;DR

This paper presents a long-term VLBI observational study of active galactic nuclei at multiple frequencies, analyzing core and jet properties to understand their spectral and brightness temperature evolution.

Contribution

It provides a comprehensive analysis of AGN core and jet properties using multi-frequency VLBI data collected over many years, offering new insights into their spectral and temperature evolution.

Findings

VLBI core flux densities and sizes characterized

Spectral properties of cores and jets analyzed

Brightness temperature evolution observed in jets

Abstract

We report on an ongoing effort to image active galactic nuclei simultaneously observed at 2.3 and 8.6 GHz in the framework of a long-term VLBI project RDV (Research and Development - VLBA) started in 1994 aiming to observe compact extragalactic radio sources in the astrometric/geodetic mode. Observations of bright extragalactic sources are carried out bi-monthly making up to six sessions per year with participation of all ten VLBA antennas and up to nine additional (geodetic and EVN) radio telescopes. Analysis of single-epoch results for 370 quasars, BL Lacs and radio galaxies is presented. We discuss VLBI core properties (flux densities, sizes, brightness temperatures), spectral characteristics of the cores and jets, evolution of brightness temperatures in the jets.